98 THE TERNS 



to conceal ourselves as far as possible in order that confidence may 

 be restored and the birds return to their nests. As far as we can tell, 

 the roseate-terns are chiefly confined to a part of the island where the 

 rock is much broken up, and on the steep sides are many nests which 

 appear to belong to this species. Not long after we have retreated to 

 our hiding-place we can see the Terns beginning to settle on the far 

 side of the island, but the clamour overhead goes on undiminished. 

 As soon as one is on its eggs, its neighbours rapidly follow suit, and 

 presently twenty or thirty birds are sitting in front of us. But without 

 any warning the babel ceases, and in perfect silence the whole body 

 rises in alarm ; presently the cries break out again, and gradually 

 confidence is restored. This is a curious characteristic of all three 

 species, which behave in exactly the same way : all rising with a 

 simultaneous rush of wings in silence, and often apparently for no 

 cause except sheer nervousness. At other times the cry of an 

 oystercatcher will put every bird on the wing. 



But now they are settling down again, and we can distinctly see 

 the long streamers of a bird whose head is hidden in a tiny cave on 

 the steep side of the rock. We mark the spot and turn our glasses to 

 the next bird, and can clearly distinguish her black bill. A long and 

 careful watch convinces us that no common-terns intrude in the 

 territory of the roseates, but, on the other hand, there is no neutral 

 ground between the two species. Within a foot or so of a sitting 

 roseate in a cleft of rock sit two common-terns on the sandy top, so 

 that practically one has to map out the limits of the two species. 

 Curiously enough, on the Skerries this is not the case, and nests of the 

 roseate are scattered about among those of the Arctic-terns, but the 

 breeding habits of these two species differ less than those of the 

 roseate and common-tern. After half an hour's work of this kind 

 we can rise from our cramped position, of course disturbing every 

 bird at once, and proceed to the ground we have been studying from 

 a distance. One by one the marked nests are identified, and now we 

 see that all those on which we have seen roseates sitting contain 



